1. Field of the Invention
The present invention relates to a circuit component built-in module and a method for producing the same. In particular, the present invention relates to a circuit component built-in module in which, for example, a circuit component is placed in an internal portion of an insulating substrate and a method for producing the same.
2. Related Background Art
In recent years, with the demand for high performance and miniaturization of electronic equipment, high density, high performance and short-distance wiring of a circuit component have been desired increasingly. Accordingly, a wiring substrate capable of including a high density, high-performance and short-distance wiring circuit component has been demanded. The formation of a multi-layer circuit may be a solution to attain a higher-density wiring substrate. However, a conventional glass-epoxy substrate requires a through-hole structure by using a drill, so that it is difficult to achieve a high density mounting. Therefore, as the most useful method for attaining a high density circuit, an inner-via-hole connection method that can connect wiring patterns between LSIs or circuit components in the shortest distance are being developed in various fields.
In the inner-via-hole connection method, only the necessary layers can be connected, and the mounting property of the circuit components is excellent (see JP63(1988)-47991A, JP6(1994)-268345A).
On the other hand, in a mounting method in which an active component such as a semiconductor chip is mounted on the surface layer of a wiring substrate, there is a limitation in attaining high density. Therefore, a mounting method of providing a substrate with a concave portion and mounting a semiconductor chip so as to be contained in the concave portion has been suggested (JP5(1993)-259372A, JP11(1999)-103147A, JP11(1999)-163249A). In this case, after the semiconductor chip is mounted in the concave portion, a sealing resin is coated so as to protect the connection portion and the semiconductor chip. Thus, sealing is performed.
However, since the substrate used in the conventional inner-via-hole connection method is formed of a resin material, it has a low thermal conductivity. Furthermore, in the circuit component built-in module, as the mounting density of the circuit substrate is higher, it is more necessary to release heat generated from the component. However, the conventional substrate cannot release heat sufficiently, thus deteriorating the reliability of the circuit component built-in module.
On the other hand, among the methods for building in a circuit component such as a semiconductor chip, in the method of providing the substrate with a concave portion so that the chip is placed therein and sealing with a sealing resin, it is necessary to perform many processes, for example, a process for forming a concave portion on the substrate, etc., which raise cost. Also, in such a method, incidence of defectiveness is increased. Furthermore, because a chip is built in, it is difficult to release heat around the chip effectively even though heat release is required. Furthermore, since the sealing resin is intervened, the property of the substrate does not have uniformity in three dimension.
If the circuit component such as a semiconductor, etc. is built in the substrate in the burying process, when the semiconductor chip is buried in the wiring pattern formed on the mold release body, a sheet flows radically and the location of the preliminarily formed via conductor may be distorted, or a wiring pattern around the chip may be disconnected or distorted. Therefore, this method has much difficulty in practice. Furthermore, there are many limitations in re-wiring in the chip built-in configuration.
Furthermore, when the mold release body is an organic film having a adhesive property, it is impossible to secure a sufficient gap for the connection portion between the wiring pattern and the semiconductor chip, and it is difficult to inject the sealing resin capable of sealing the connection portion, and thus the reliability of the connection portion cannot be obtained sufficiently.
On the other hand, in the module in which a circuit component is built in, since there is a difference in the coefficient of thermal expansion between the substrate and the circuit components, it is not possible to secure the reliability of the circuit component when the circuit component is buried.
It is an object of the present invention to provide a circuit component built-in module capable of mounting circuit components with high density, having a high heat releasing property and a high reliability and a method for producing the same.
In order to attain the above-mentioned object, the circuit component built-in module of the present invention includes an insulating substrate including a mixture of an inorganic filler and a thermosetting resin; a wiring pattern formed on at least one principal surface of the insulating substrate; and a circuit component placed in an internal portion of the insulating substrate and electrically connected to the wiring pattern; and the mixture includes a second mixture that seals at least a connection portion between the wiring pattern and the circuit component and a first mixture forming a region excluding the second mixture in the insulating substrate. In this configuration, the amount of an inorganic filler contained in the first mixture is larger than the amount of the inorganic filler contained in the second mixture.
According to the configuration of the circuit component built-in module, heat generated from the circuit component is released by the inorganic filler swiftly, so that a circuit module having high reliability can be realized. Furthermore, among the two kinds of mixtures forming the insulating substrate, the second mixture having a smaller content of an inorganic filler seals the wiring portion connecting to the circuit component, so that a highly reliable connection portion free from the disconnection can be obtained.
Furthermore, by selecting the inorganic filler, it is possible to change the thermal conductivity, coefficient of linear thermal expansion, dielectric constant, breakdown voltage or the like. Therefore, since it is possible to make the coefficient of linear thermal expansion of the insulating substrate substantially the same as that of the semiconductor device, a circuit component built-in module preferably integrates a semiconductor device. Furthermore, since it is possible to improve the thermal conductivity of the insulating substrate, the circuit component built-in module preferably includes a semiconductor device requiring the heat release. Furthermore, since it is possible to lower the dielectric constant of the insulating substrate, a circuit component built-in module for high frequency is preferably provided.
Furthermore, in the case of a circuit component built in module including a semiconductor and a chip capacitor as the circuit components, it is possible to reduce the noise of the electric signal by shortening the distance between the semiconductor chip and the chip capacitor. Furthermore, it is preferable that the wiring patterns are formed on both principal surfaces of the insulating substrate, and an inner via conductor for electrically connecting the wiring patterns on both principal surfaces is provided.
Furthermore, in general, the semiconductor chip has a problem in terms of KGD (known good die) and handling, raising the cost. However, with the circuit component built-in module of the present invention, even if the bare semiconductor chip is used as the circuit component, it is advantageous in that the quality check is carried out easily. Furthermore, re-wiring is performed easily, so that it is possible to attain various LGA electrodes having less restriction in designing.
Furthermore, it is preferable in the circuit component built-in module of the present invention that the second mixture is intervened in the boundary portion between the wiring pattern and the first mixture. According to such a preferable configuration, it is possible to prevent disconnection and distortion, when the circuit component is buried. In particular, it is advantageous when the circuit component is buried by forming a wiring pattern and circuit component on the base material such as a mold release carrier and bringing the mold release carrier into contact with the first mixture that the disconnection or distortion of the wiring pattern does not occur even if the base material such as resin film that stretches is used, because the circuit component and wiring pattern are sealed and fixed with the second mixture.
Furthermore, it is preferable in the circuit component built-in module of the present invention that the inner via conductor includes a conductive resin composition. This preferable configuration facilitates the production. In this case, it is preferable that the conductive resin composition includes one selected from the group consisting of gold, silver, copper and nickel as a conductive substance, and an epoxy resin as a resin substance. These metals have low electric resistance. Epoxy resin is excellent in thermal resistance or electric insulating property.
Furthermore, it is preferable in the circuit component built-in module of the present invention that the circuit component includes at least one active component. According to such a preferable configuration, it is possible to integrate a circuit component having a desired function.
In this case, it is further preferable that the active component includes a bare semiconductor chip, and the bare semiconductor chip is flip-chip bonded to the wiring pattern. Furthermore, it is preferable that a thermal via conductor is formed on the rear side of the bare semiconductor chip. This preferable configuration provides an insulating substrate excellent in heat releasing property, and is employed for a bare semiconductor chip that generates a large amount of heat because the heat releasing property of the bare semiconductor chip is improved.
Furthermore, it is preferable in the configuration of the circuit component built-in module of the present invention that the first mixture includes 70 weight % to 95 weight % of an inorganic filler and the second mixture includes 50 weight % to 90 weight % of an inorganic filler. According to the preferable configuration, the heat generated from the circuit component is released swiftly by the first component in which an inorganic filler is filled with high density, so that a highly reliable circuit component built-in module can be realized.
Furthermore, it is preferable in the configuration of the circuit component built-in module of the present invention that the inorganic filler includes at least one selected from the group consisting of Al2O3, MgO, BN, AlN, and SiO2. According to such a preferable configuration, an insulating substrate excellent in the heat release property can be obtained. When MgO is used for the inorganic filler, it is possible to increase the constant of linear thermal expansion. Furthermore, when SiO2 (in particular, amorphous SiO2) is used for the inorganic filler, it is possible to reduce the dielectric constant of the insulating substrate. Furthermore, when BN is used for the inorganic filler, it is possible to reduce the constant of linear thermal expansion.
Furthermore, it is preferable in the configuration of the circuit component built-in module of the present invention that the thermosetting resin includes at least one resin selected from the group consisting of an epoxy resin, a phenol resin, a cyanate resin and a polyphenylene ether resin because these resins are excellent in thermal resistance or insulating property.
Furthermore, it is preferable in the configuration of the circuit component built-in module of the present invention that the wiring pattern includes copper. Copper has a low thermal resistance, so that a fine wiring pattern can be formed. Furthermore, when, for example, copper is used for the wiring pattern, the surface of a copper foil that is in contact with the substrate is preferably roughened.
Furthermore, it is preferable in the configuration of the circuit component built-in module of the present invention that the wiring pattern has two layers or more including a layer formed of copper and a layer including one metal selected from the group consisting of gold, Sn, Pb, and Ni. For example, a wiring pattern formed of copper foil may be oxidized in the thermal treatment at the time of mounting after formation of patterns. However, by forming a structure having two layers or more plated by nickel, gold, or the like, oxidation can be prevented. Furthermore, it is possible to improve the connecting reliability to the circuit component.
Furthermore, it is preferable in the configuration of the circuit component built-in module of the present invention that the wiring pattern is buried in the insulating substrate. Thus, the wiring pattern is stable and the reliability can further be improved.
Furthermore, it is preferable in the configuration of the circuit component built-in module of the present invention that a region excluding an external lead electrode in the wiring pattern is covered with a protective film. In this case, it is preferable that the protective film includes a material including a resin or resist. According to such a preferable configuration, the wiring pattern is constrained by the protective film and thus the connection between the circuit component and the wiring pattern is stable and the reliability is further improved.
Furthermore, it is preferable in the configuration of the circuit component built-in module of the present invention that the circuit component includes one component selected from the group consisting of a chip resistor, a chip capacitor, and a chip inductor. By using the chip type circuit component as the circuit component, it is possible to bury the circuit component in the insulating substrate easily.
Furthermore, it is preferable in the configuration of the circuit component built-in module of the present invention that the first mixture has a thermal conductivity of 1 W/mK to 10 W/mK. According to such a preferable configuration, the thermal conductivity close to that of the ceramic substrate can be obtained and the substrate high in a heat releasing property can be obtained.
Furthermore, it is preferable in the configuration of the circuit component built-in module of the present invention that the coefficient of linear thermal expansion of the second mixture is in between the coefficient of the circuit component and the coefficient of the first mixture, because the second mixture that intervenes between the circuit component and the first mixture serves as a relaxing substance for thermal stress.
Furthermore, it is preferable in the configuration of the circuit component built-in module of the present invention that a wiring substrate is laminated on at least one principal surface to form a multilayer wiring structure. Thus, the circuit component can be mounted with higher density.
Furthermore, it is preferable in the configuration of the circuit component built-in module of the present invention that the wiring substrate is a ceramic multilayer wiring substrate. Thus, by using the high frequency property that is an excellent property of the ceramic substrate, it is possible to realize an RF module having a high performance and high function.
Alternatively, it is preferable in the configuration that the wiring substrate includes one or a plurality of circuit component built-in modules mentioned above. According to such a configuration, since the plurality of circuit component built-in modules of the present invention are laminated, it is possible to realize a highly reliable multilayer circuit component built-in module in which the circuit components are mounted with high density.
Furthermore, it is preferable in the configuration of the circuit component built-in module of the present invention that the wiring pattern connected to the circuit component is located on the principal surface on which the wiring substrate is laminated. Thus, the wiring pattern connecting to the circuit component is constrained by the wiring substrate, the connection between the circuit component and the wiring pattern is stable.
Alternatively, it is preferable that the wiring pattern connecting to the circuit component is located on the principal surface on which the wiring substrate is not laminated, and the protective film that covers the wiring pattern is provided. Thus, the wiring pattern connecting to the circuit component is constrained by the protective film, so that the connection between the circuit component and the wiring pattern is stable.
According to another aspect of the present invention, a radio device of the present invention includes the circuit component built-in module having any of the configurations mentioned above. According to such a configuration, a highly reliable radio device can be provided. In particular, it is preferable that the circuit component built-in module is an RF module using a ceramic substrate, because it is possible to realize a high performance and high function radio device.
According to another aspect of the present invention, a method for producing the circuit component built-in module of the present invention includes placing a circuit component on a first wiring pattern formed on one principal surface of a base material for connection therebetween and sealing at least a connection portion between the first wiring pattern and the circuit component with a second mixture including an inorganic filler and an uncured thermosetting resin; subsequently, allowing a first mixture including an inorganic filler and an uncured thermosetting resin to face the principal surface of the base material on which the circuit component is formed and pressing the base material to bury the circuit component in the first mixture; wherein the amount of the inorganic filler contained in the first mixture is larger than the amount of the inorganic filler contained in the second mixture.
With this method, the circuit component built-in module of the present invention can be produced.
It is preferable in the method for producing the circuit component built-in module of the present invention that the first mixture includes 70 weight % to 95 weight % of an inorganic filler and the second mixture includes 50 weight % to 90 weight % of an inorganic filler.
Furthermore, it is preferable in the method for producing the circuit component built-in module of the present invention that in sealing, by injecting an uncured second mixture into the connection portion between the first wiring pattern and the circuit component and curing the second mixture, the connection portion and the side part of the first wiring pattern and the circuit component are sealed. According to this method, since the location relationship of the first wiring pattern, circuit component and connection portion is fixed by the second mixture, in burying, it is possible to prevent the distortion of the connection portion between the circuit component and the first wiring pattern. Thus, the circuit component built-in module having a high reliability can be provided.
It is preferable in the method for producing the circuit component built-in module of the present invention that the sealing includes injecting an uncured second mixture into the connection portion between the first wiring pattern and the circuit component and curing the second mixture; molding the second mixture into a sheet of the mixture, covering the entire part of the circuit component and the first wiring pattern on the base material; and curing the second mixture sheet by heating and pressing. According to such a method, the entire part of the first wiring pattern is sealed with the second mixture, so that it is possible to prevent the first wiring pattern from being damaged when it is buried.
It is preferable in the method for producing the circuit component built-in module of the present invention that the sealing includes injecting the uncured second mixture into the connection portion between the first wiring pattern and the circuit component and the entire part of the first wiring pattern and curing thereof. According to such a method, the entire part of the first wiring pattern is sealed with the second mixture, so that it is possible to prevent the first wiring pattern from being damaged when it is buried.
It is preferable in the method for producing the circuit component built-in module of the present invention that holes are provided on the base material, and wherein the sealing includes injecting the second mixture via the hole from the opposite surface of the principal surface of the base material on which the circuit component is provided. According to such a method, it is possible to fill the second mixture easily in the gap between the circuit component and the first wiring pattern.
It is preferable in the method for producing the circuit component built-in module of the present invention that the first mixture is formed into a plate before the burying. According to such a method, by burying the circuit component in the first mixture that is molded in a form of plate, the circuit component built-in module can be produced easily.
It is preferable in the method for producing the circuit component built-in module of the present invention that the burying includes placing the first mixture into a mold, allowing the first mixture in the mold to face the principal surface on which the circuit component is formed and pressing the base material; and removing the first mixture from the mold. According to such a method, as compared with the method including a process for forming the first mixture into a form of a plate, the process can be simplified because the formation of the first mixture and the burying the circuit component are performed together.
It is preferable in the method for producing that the circuit component built-in module of the present invention further includes forming an inner via conductor in the first mixture, and forming a second wiring pattern that connects to the first wiring pattern via the inner via conductor on the surface of the first mixture opposite to the surface on which the circuit component is buried. Thus, a circuit component built-in module capable of mounting the circuit component with high density can be provided.
Furthermore, it is preferable in the method that the forming of the inner via conductor is carried out after the burying, and includes forming a through-hole for inner via conductor, which reaches the first wiring pattern from the surface of the first mixture opposite to the surface in which the circuit component is buried; and filling a thermosetting conductive substance in the through-hole for the inner via conductor. According to such a method, by forming the inner via conductor after burying, the inner via conductor without distortion can be produced.
Furthermore, it is preferable that the conductive substance includes a conductive resin composition. Thus, it is possible to product the inner via conductor by a simple process of filling the conductive resin composition in the through hole and curing thereof, thus facilitating the production of the circuit component built-in module easily.
It is preferable that the method includes, before forming the through-hole for the inner via conductor, recognizing the position of the first wiring pattern by X-ray irradiation to determine the position for forming the through-hole for the inner via conductor. According to such a method, since the position of the inner via conductor can be determined with high accuracy, it is possible to provide a circuit component built-in module having a high connection reliability.
It is preferable that the method further includes forming a through-hole for thermal via conductor in the first mixture, before burying, in forming the inner via conductor, a conductive substance is filled in the through-hole for the inner via conductor and at the same time, a thermal conductive substance is filled in the through-hole for the thermal via conductor. According to such a method, it is possible to provide a circuit component built-in module having a high thermal releasing property in the vicinity of the circuit component. Furthermore, the filling of the thermal conductive substance into the through-hole for thermal via conductor and the filling of the conductive substance into the through-hole for inner via conductor are performed at the same time, and thus the process is simplified.
It is preferable in the method that the thermal conductive substance to be filled in the through-hole for a thermal via conductor and the conductive substance to be filled in the through-hole for the inner via conductor include a metal particle and a thermosetting resin, and the content of the metal particles of the thermal conductive substance to be filled in the through-hole for the thermal via conductor is higher than the content of the metal particles of the conductive substance to be filled in the through-hole for the inner via conductor. Furthermore, it is preferable that the diameter of the through-hole for the thermal via conductor is larger than the diameter of the through-hole for the inner via conductor.
It is preferable in the method that a mold release carrier is used for the base material. Thus, the circuit component built-in module can be provided easily.
In this case, it is further preferable that the mold release carrier is an organic film. If the organic film is used as the mold release carrier, since the organic film is an insulating material, it is possible to perform a connection continuity check of the circuit components mounted on the wiring pattern formed on the mold release film.
Alternatively, it is preferable that the mold release carrier is a metal foil. In this case, as compared with the case where the resin film is used for the mold release film, the mold release carrier is not stretched, the wiring pattern can be transferred without distortion in the burying process. Furthermore, since the metal foil does not have the adhesive property unlike the organic film, when the second mixture is injected between the circuit component and the first wiring pattern, the fluid property of the second mixture is not impaired, and thus, the connection portion between the circuit component and the first wiring pattern is securely sealed with the second mixture without a gap.
Furthermore, it is preferable that the method further includes forming a peel layer on the metal foil before forming the first wiring pattern on the metal foil. Thus, the mold release carrier easily can be removed.
It is preferable in the method that the inner via conductor is formed before burying, and the mold release carrier is provided with one or a plurality of holes that serve as an ejecting hole for the first mixture in burying. According to such a method, in the process of burying, when the circuit component is buried in a state in which the mold release carrier is in contact with the first mixture, the portion of the first mixture in which the circuit component is buried is ejected from the holes of the mold release carrier. Thus, even if the inner via conductor is formed before burying, the distortion of the inner via conductor can be reduced radically. Thus, it is possible to provide a highly reliable circuit component built-in module.
Furthermore, it is preferable in the method that the multilayer wiring substrate is used for the base material. According to such a method, the circuit component is connected to the wiring formed on the principal surface of the multilayer substrate and the circuit component is buried in a state in which this multilayer substrate is in contact with the first mixture, so that the circuit component built-in module in which multilayer substrate is laminated can be provided.
In this case it is further preferable that the multilayer wiring substrate is a ceramic multilayer wiring substrate. Thus, it is possible to use the property of the high frequency of the ceramic substrate, and it is possible to realize the circuit component built-in module with the high performance and multifunction RF module.
Furthermore, it is preferable in the method that forming the second wiring pattern is performed after forming the inner via conductor, and includes laminating a metal foil on the surface of the first mixture opposite to the surface on which the circuit component is buried, heating at the temperature where the thermosetting resin of the first and second mixtures and the conductive substance of the inner via conductor are cured; and forming the metal foil into the second wiring pattern. Thus, the second wiring pattern of a desired pattern easily can be formed.
Alternatively, it is preferable in the method that forming the second wiring pattern is performed after forming the inner via conductor, and includes forming the second wiring pattern on one principal surface of the mold release carrier for the second wiring pattern, allowing the mold release carrier to face the principal surface on which the second wiring pattern is formed to the surface opposite to the surface on which the circuit component is formed and pressing the releasing carrier; heating at the temperature where the thermosetting resin of the first and second mixtures and the conductive substance of the inner via conductor are cured; and peeling off the mold release carrier.
According to such a method, the second wiring pattern is formed by the method for transferring the wiring pattern formed on the mold release carrier, so that the second wiring pattern can be buried in the first mixture. Thus, the second wiring pattern is stable and the circuit component built in module having a high reliability can be provided.
It is preferable that the method further includes forming a protective film on the region excluding the external lead electrode on the first wiring pattern. Thus, in particular, the connection between the circuit component and the first wiring pattern is stable, thus improving the reliability.
It is preferable in the method that the first wiring pattern is formed of copper foil. Furthermore, it is preferable that the second wiring pattern is also formed of copper foil. In this case, it is preferable that the method further includes forming at least one layer of a metal selected from the group consisting of Au, Sn, Pb, and Ni by electrolytic plating on the wiring pattern formed of a copper foil. Thus, the circuit component and the wiring pattern can be connected strongly.
It is preferable in the method that after forming the inner via conductor on a plate obtained by sealing and burying, the base material is peeled off to produce circuit component built-in substrate; laminating a plurality of the circuit component built-in substrates to produce a multilayer circuit component built-in substrate, and forming a second wiring pattern on the principal surface of the multilayer circuit component built-in substrate on which the first wiring pattern is not formed. According to such a method, it is possible to provide a multilayer circuit component built-in module including a plurality of circuit component built-in modules of the present invention.